Method of and apparatus for controlling alternating currents



DeC-

W. A. EATON METHOD OF AND APPARATUS FOR CONTROLLING ALTERNATING CURRENTS Filed March 25, 1920 2 Sheets-Sheet. l

FIG. 6

FIG- 3 Dec. 15,1925. v 1,565,316

w. A. EAATON METHOD OF AND APPARATUS FOR CONTROLLING ALTERNATING CURR'BN'I'S Filed March 25, 1920 2 Sheets-Sheet 2 FIG. 3

FIG: 5

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Patented Dec. 15, 1.925.

UNITED STATES PATENT, OFFICE.

WILLIAM A. EATON, OF ARLINGTON, VIRGINIA, ASSIGNOR TO RADIO CORPORATION OF AMERICA, 01? NEW' YORK, N. Y., A CORPORATION OF DELAWARE.

METHOD OF AND APPARATUS FOR CONTROLLING. ALTERNATING CURRENTS.

Application filed March 25, 1920. Serial No. 368,681.

To all whom it may concern 7 Be it known that I, WILLIAM A. EATON, a citizen of the United States, and resident of Arlington, in the county of Alexandria and State of Virginia, have invented certain new and useful Improvements in Methods of and Apparatus for Controlling Alternating Currents, of which the following is a specification.

My invention relates to a new and improved method of quickly interrupting or decreasing the current in an oscillatory circuit without interrupting the source of supply, and is of particular value as an interrupter of large energy currents.

A particular object of this invention is an improvement in the method of radio signaling by the are or similar systems, though other applications will readily suggest themselves after the description following.

In certain types of generators of alternat-I ing currents it is not practical or desirable to interrupt the source of supply in order to interrupt or decrease the alternating current in a work circuit as for instance in the are system of radio signaling it is not practical to interrupt. the source of supply in n'laking signals as the arc will be extinguished and further signaling cannot be done until the are has been remade by striking either manually or mechanically. Likewise in the use of a high frequencyalternator for radio signaling, it may be desirable to keep a constant load on the machine in order to aid in maintaining constant speed and therefore an unvarying wavelength for if the output of the generator is interrupted or decreased in making signals, the machine will tendtowards a varying speed with resulting variations in wavelengths.

I am particularly familiar with thefidifficulties now existing in the use of the are system for radio signaling and a recital of these difficulties and how my invention overcomes them will aid towards a. clear under standing of its value inone of its applica tions. 7

The methodnow in general use for high power systems is to make a slight change in wave length between 'dots and dashes by short circuiting a few turns of the antenna loading inductance creating a so-called back wave or compensating wave in contradistinction to the. direct or signaling wave. This slight change in wave length does not per-v ceptlbly alter the antenna current or the energy of radiation, and reception therefore depends upon the use of a selective receiver signaling Wave from which he reads thesignals and the back or compensating wave from which he interprets the spaces between dots and dashes. However, there are restrictions to the amount of change of wave length permissible in practice as in short circuiting the turns of inductance to change wave length considerable energy is interrupted which energy increases in proportion to the change in wave length and the design of a key to handle the arcing produced at the key contacts has been a long and not yet completely successful effort in the radio art, sothat thechange in wave length is made as small as possible, as a compromise on key design. Also, thegreater the change in wave length for signaling the wider the band of interference of a given station, and since the matter of interference is a vital one in the minds of all radio engineers oflto-day, the change in wave length method of signaling is not looked upon with favor and is only retained in use for want of a better method.

In the practice of my invention, I propose to suppress the back or compensating wave and emit but one wave in radio signaling, or suppress the energy in the work circuit in any system where it is desired to quickly interrupt or decrease the working energy without interrupting the source, and it is a feature of my invention that I accomplish this, simply and effective ly and yet reduce contact arcing to a degree where simple key contact apparatus can replace the complicated quickly destroyed apinvention applied to an arc signaling system; Figure 3 illustrates the invention applied to a signaling system employing any source of sustained oscillations and using a loop antenna system, Figures 4 and 5 show modifications of the are signaling circuit illus trated in Fig. 2; and Figure 6 shows an application of the invention in which the sustained oscillations may be shifted to any desired number of independent work circuits. Like characters of reference have been used to indicate like parts throughout the several figures.

In Figure 1, S is a source of alternating current shown as a high frequency generator coupled to the circuit through a transformer but this may be any source such as a high frequency generator connected directly in the circuit or an are as shown in Figure 2 or a vacuum tube generator as shown in Figure 3 or even the well known spark generator. The circuit S, R 2, L C, is an absorbing circuit or idling circuit containing resistance R, inductance L and capacity 0,. The circuit S, R, 1, T, L, C, is a work circuit containing resistance R, inductance L, capacity C, and any device M wherein it is desired to cause the energy in the work circuit to do work, T simply being indic ative that the device may be coupled to the circuit through a transformer. 1 and 2 are good contacts inserted in the circuits. K is key carrying a contact 3 capable of being thrown in contact with either 1 or 2, short circuiting resistance R or R as contact is made with 1 or 2 respectively.

By so short circuiting the resistance in one circuit and inserting it in the other, the one is made a good receiver for a flow of oscillatory circuits, while the other circuit is rendered aperiodic and therefore sup presses to a desired practical extent the flow of oscillatory current, and vice versa, without interrupting the source. The switching is accomplished with a less degree of deleterious arcing at the contacts than is now common in the switching means used for change of frequency signaling in arc radio systems. The resistances R and R are chosen having such values with respect to the other constants of the circuits as will suppress the oscillatory currents to the de sired extent in the particular system it is desired to so operate. In other proposed systems of absorbing circuits it has been necessary to make the capacity of the con denser 0, equivalent to or slightly greater than the capacity of the condenser C, or equivalent to the combined concentrated and distributed capacity of the work circuit, in order to make this circuit particularly re-- ceptive and ready to accept the energy from the work circuit. This necessity for a large capacity in an absorbing circuit may be par ticularly undesirable in handling large powers as extremely large and expensive condenser installations will be required, and this cannot be avoided as the large capacity is a function upon which the success of op eration depends.

In my system the capacity of the condenser in the absorbing circuit does not have the same vital weight in the functioning as the oscillations are driven out of the work circuit by a resistance opposing oscillations, so that the capacity may be made smaller, being limited only by such requirements, in the case of the arc, of having suiiicient capacity to absorb enough energy to keep the are from extinguishing or, in the case of the alternator, where it may not be compulsory to keep full load on the machine and yet not desirable to reduce the load to zero or nearly so, the capacity of the absorbing cirouit can be made smaller in proportion as these requirements have to be met.

The key K may be any suitable form, operative by hand or through a mechanical, magnetic, or pneumatic control, of which there are numerous forms for ordinary or high speed operation. It may be desirable in handling large powers to fit the key with either a magnetic or air blast blow-out to keep arcing under control and the key may be fitted with any common form of device for retarded breaking until contact is made in shifting from one contact to the other.

Figure 2 differs from Figure 1 in that the work circuit here represented as the open or radiating antenna circuit C, L, 1, R, S, G, of a radio transmitter and has an are as a source of alternating current; however although I have given a number of diagrams as examples of applications of my system, I do not wish to be limited to the particular circuits and apparatus illustrated, as there are many possible combinations in which this principle may be employed, and many possible changes of application from one form of circuit to another all readily suggesting themselves to those skilled in the art. In applying the circuit of Figure 1 to an arc signaling system it will be desirable in some installations to insert a resistance R, in the absorbing or idling circuit of such value that the total resistance of this circuit, when the resistance R, is shunted out with the key K in the position where contacts 2 and 3 are brought together, may be equal or substantially equal to the total resistance of the work circuit when the re sistance R is short circuited in order that a proper balance between the circuits may be obtained. This is particularly valuable in radio systems where unbalances tend to give ragged notes in signaling.

Figure 3 differs from Figure 2 in that a closed or loop antenna is shown as part of the work circuit containing capacity C, source S, inductance L, resistance It and tion.

contact 1. The source here is illustrative of how a vacuum tube oscillator may be the source of alternating current.

Figure t is the same as Figure 2 except the inductances L of the work circuit and L of the absorbing circuit are diagrammatically shown as in close proximity, such as being wound on the same frame for the purpose of saving space. Thisfeature is indicative of the effectiveness of this inven- In otherpropos ed absorbing circuit systems it has been found necessary to sepa rate the inductance out the two circuits to a considerable extent in order to prevent the coupling between these elements from set:

1 ting up measurable oscillations in the work circuit at times when it was desired for this circuit to remain idle.

Figure is a modification of Figure 4: wherein the inductance L, of the absorbing circuit is arranged to be in series with the inductance L of the work circuit when the work circuit is in operation at the time that he K has contact 3 in connection with contact 1, thereby reducing the installation space necessary for the antenna loading inductance and improving the etliciency of the system.

Figure 6 is a modification of Figure 1, an arrangenient being shown for employing a plurality of work circuits witha single absorbing or idling circuit. The key K may be supplied with additional contacts 4 and 5 and the additional work circuit R 4, T

C provided. Oscillations can be produced in device M or M, depending upon the position of switch K.

Having thus described my invention, what I claim and desire to secure by Letters Patent of the United States is:

1. In a system employing oscillatory currents the method of producing oscillations in any one of a plurality of work circuits which consists in removing a resistance from the desired work circuit at substantially the same instant that a resistance is inserted in the idling circuit and interrupting the 0s cillations in the work circuit by the reverse process without interrupting the source, sub stautially as set forth.

2. In a system employing oscillatory currents the method of suppressing oscillations in a work circuit without materially changing the load on a source oi continuous oscilhiti'ons which consists in rendering the work circuit non-oscillatory and maintaining a constantload on the source of diverting oscillations into an idling circuit of electrical capacity substantially equal to that of the work circuit, substantially as set forth.

3. In a system employing oscillatory currents the method of suppressing oscillations in any one of a plurality of work circuits receiving oscillations from a single source, which consists in rendering non-oscillatory source which consists in rendering non-oscillatory an idling circuit and. rendering oscillatorythe desired Work circuit to divert the oscillations from said idling circuit to said desired work circuit.

5. Ina system of radio transmission the combination of a source of radio frequency. oscillations, an ldhng circuit, an antenna circuit, and means for entirely suppressing oscillations in said antenna circuit and diverting them into said idling circuit com-- prising a short circuited resistance in series with said antenna and means for removing said short circuit.

6. Ina system of radio transmission the combination of a source of radiofrequency oscillations, ar. idling circuit, an antenna circuit, and means for entirely suppressing oscillations in said antenna circuit and (nverting them into said idling circuit comprising a short-circuited resistance in series with said antenna and signaling means for rendering said short circuit ineiiective.

7. In a system employing oscillatory currents the combination of a source of oscillations, a Work circuit having a resistance in series therewith, an idling circuit having a resistance in series therewith, and means for shifting energy from said work circuit to said idling circuit and the reverse process comprising means for alternately removing said resistance from a series relation with said circuits.

8. In a system employing oscillatory currents the combination of a source of oseil lations, a work circuit, an idling circuit, resistances in series with said circuits, and means for shifting energy back and forth between said circuits comprising means for alternately short-circuiting said resistances- 9. The combination in a radio signaling system of a source of continuous radio frequency currents, a signaling circuit and an absorption circuit associated therewith, both of said circuits being adapted to absorb the operating energy output of said source, and means for varying only one of the constants of said signaling circuit while maintaining its electrical period constant.

10. In a radio signaling system, the combination with a sourceof oscillatory currents, of a loading inductor in series therewith, an energy-consuming circuit including a resistance device and a condenser substantially tuned to resonance with said inductor and connected across said source and inductor, a work circuit including a tuning coil, condensive reactance means and energyconsuming means also connected across said source and inductor, said inductor, tuning coil and condensive reactance means being also substantially tuned to resonance, and means for decreasing the resistance of said resistance device and rendering said work circuit substantially non-oscillatory, and vice versa, for causing the oscillations to shift from one circuit to the other.

11. In an electrical system, a switching device comprising a pair of main contact members and a co-acting movable Contact member, an antenna circuit connected to one of said main contact members, a ground circuit including a source of oscillations therein connected to said movable contact member and an idling circuit connected in shunt to said source of oscillations, one terminal thereof being connected to the remaining main contact member, said switching device being such that the breaking of the contact with one main contact member is retarded until contact is made with the other.

12. In an electrical system, a switching device comprising a pair of main contact members and a co-acting movable contact member, an antenna circuit connected to one of said main contact members, a ground circuit including a source of oscillations therein connected to said movable contact member, an idling circuit connected in shunt to said source of oscillations, one terminal thereof being connected to the remaining main contact member, and a controlling resistor serially included in said idling circuit and connected between said remaining contact member and said movable contact member, said switching device being such that the breaking of contact with one main contact member is retarded until contact is made with the other.

13. In an electrical system, a switching device comprising a pair of main contact members and a co-acting movable contact member, an antenna circuit connected to one of said main contact members, a ground circuit including a source of oscillations therein connected to said movable contact member, an idling circuit connected in shunt to said source of oscillations, one terminal thereof being connected to the remaining main contact member, a controlling resistor connecting said last-mentioned contact member and said movable contact member and energy absorbing means serially included in said idling circuit, said switching device being so designed that the breaking of contact with one main contact member is retarded until contact is made with the other.

14. The method of transferring the energy of an arc-type oscillation generator from a main work circuit to an auxiliary circuit, which consists in momentarily connecting the previously de-energized circuit in shunt to the previously energized circuit, and then rendering said previously energized circuit substantially non-oscillatory.

15. The combination in a radio signaling system of a source of continuous radio fre quency currents, a signaling circuit and an absorption circuit associated therewith, and means for simultaneously varying in opposite senses one of the constants of each of the two circuits while maintaining the natural periods of said circuits substantially constant.

IVILLIAM A. EATON. 

